1. Field of the Invention
The present invention relates to a personal fall-arrest safety anchor which is permanently attached to and encircles a roof rafter. A preformed elastomeric flashing for weather-proofing, an overlapping bracing bar, and mounting devices to enhance safety of the anchor are also described.
2. Description of the Prior Art
Government regulations require fall prevention systems for roofers or others working on a roof. Certain fall restraint systems of the anchor type described herein currently are required by regulation to have a minimum load strength of 5400 pounds. Yet these requirements are meaningless if the anchor cannot be safely installed. To be safely installed, placement of the device on a properly installed roof rafter of appropriate dimension and load carrying capability is obviously and minimally required.
However, for building economy, today's roofing joists typically come pre-framed in "A"-type braces, often constructed of 2".times.4" lumber. Use of such preassembled roof trusses requires strict adherence by the builder to the manufacturer's engineering specifications and limitations. For example, many manufacturers do not allow drilling of any holes through the truss rafters, which severely limits the design of retrofit roof anchors.
The prior art shows roof anchors capable being installed onto pitched roofs and rafters of variable size. These anchors teach the use of members extending generally downwardly to embrace various roof elements, usually rafters. However, in order to accomplish their intended purpose and create both an operable and safe anchor installation, each of these devices requires the use of fasteners, usually nails or a threaded bolt of appropriate dimension, in order to secure the device to the roof structure. However, in the event of fastener failure or improper installation, e.g. bolt shearing, mechanical stripping of the bolt thread, nails pulling from weak lumber, or failing to install the fastener entirely, none of the devices found in the prior art would be capable of preventing a fall. The present invention discloses fail-safe features to allow an anchor to fulfill its intended purpose should fasteners fail, by a means of encircling a rafter or a preassembled truss.
U.S. Pat No. 5,370,202 issued Dec. 6, 1994 to Nichols discloses a fall arrest lifeline roof anchor, as does a prior patent issued to Nichols on Sep. 28, 1993 (U.S. Pat No. 5,248,021). A primary embodiment in each patent is shown as a bracket having flat parallel legs, further having preformed nail and bolt holes, for embracing a rafter, and, an apertured upwardly projecting central portion for connection of a standard snap hook or carabiner to which a lifeline can be attached. In the absence of fasteners; little force needs to be applied to the carabiner in order to slip the legs of the anchor off the rafter. Furthermore, any forces applied to the device are transmitted to the fasteners, rather than the legs of the device itself, increasing the chance of failure.
A second embodiment of the Nichols patents illustrate that the bottom free-end portions of the legs can be bent inward underneath the bottom of the rafter alleging greater strength and resistance to twisting or swinging movement of the bracket relative to the rafter. However, after spreading the legs sufficiently for installation over the rafter, any loss of resiliency in the material from which the anchor is made will cause the legs to stay spread, adding unwanted tension and shearing forces against the fasteners. Loss of resiliency and the fastener would then result in loss of the minimal advantage gained by bending the legs of the anchor inward by allowing the legs to slip by the rafter.
U.S. Pat. No. 5,143,171 issued Sep. 1, 1992 to Glynn et al. discloses a lifeline safety system for a pitched roof which employs a "J"-shaped bolt to secure the bracket assembly to the roof. A nut with a pair of arms is used to torque the nut to the bolt beneath a rafter. U.S. Pat. No. 4,249,713 issued Feb. 10, 1981 to Glynn et al. discloses a roof peak metal strap with outwardly extending legs to be attached to roof joists. A central portion of the strap extends upwardly at the roof peak to which a safety line may be attached.
U.S. Pat. No. 3,217,833 issued on Jun. 29, 1964 to Smith shows a sliding safety anchor for use with steel rails. U.K Pat. Application No. 2219826 by applicant Campbell published Dec. 20, 1989 shows a multiple part anchoring system comprising a clamp attached to an underlying beam and a shaft which interconnects with at least one extension of the clamp. The shaft which extends through the external covering of the roof is provided with an eyelet to which to attach a harness.
However, none of the above patents disclose a unitary means of encircling a joist so as to provide a fail-safe means of anchoring a fall-arrest lifeline. Furthermore, manufacturers' engineering requirements for pre-assembled 2".times.4" brace-member trusses often prohibit the drilling of holes into the 2".times.4" brace members, which may cause weakening of the truss and an inability to carry its load requirements. Hence, anchors which disclose the use of large diameter fasteners passing through the lumber would result in a safety hazard. Less secure fastening means such as nails or screws would be necessary. Furthermore, none of the above referenced patents disclose an independent overlapping plate to reduce the chances of fastener pull-out by a torque or force upon the anchor.
Finally, none of the above referenced patents disclose a flashing preformed to an anchor for weather-proofing a roof. Water damage to a roof joist member would further the chances of an anchor's fastening means being loosened or damaged.
None of the above referenced inventions and patents, taken either singly or in combination, is seen to describe the instant invention as claimed.